ICHTHYOLOGY. 



The names of the fins which may not improperly be 

 called their arms, have been distinguished in the following 

 manner. The dorsal, or back-fius ; the pectoral, or breast- 

 fins ; the ventral, or belly-fins ; the anal, or vent-fins ; and 

 the caudal, or tail-fin. And lastly, the Cartilaginous fishes 

 have only a membranaceous skeleton instead of a boney one, 

 as their name naturally imports. 



There are some kinds of Fish which have the singular 

 property of being able to exist for a considerable time out of 

 the water, as is the case with the Eel and the Flying Fish. 

 It must be supposed that there is a corresponding difference 

 in the organic conformation of the gills. 



Fish are to be considered, by those conversant with 

 mechanicle principles, as being admirably adapted by their 

 form for the quickest and easiest transitions and motion. 

 For this purpose they are shaped like a wedge, capable of 

 cutting and dividing the medium through which they move, 

 the nose being in general pointed, and the rest of the body 

 gradually widening in breadth ; this peculiar shape being 

 the most favourable for swiftness of motion. Some species 

 of Fish have their mouths placed under their head, as the 

 Remora, or Sucking Fish, by which they can adhere very 

 strongly to objects which they seize. By this circumstance 

 the Shark is obliged to turn himself over, with his body up, 

 before he can make his bite, and from this delay the life of 

 the person devoted to his fury is sometimes saved. 



The tail may be considered as a double fin, acting up- 

 wards and downwards ; it can also impart a sudden motion 

 forwards, in the manner of a scull or oar, such as is used by 

 boatmen at the stern of their boats. The most surprizing 

 efforts of all these, and depending upon the motion of the 

 tail, is that which is exerted by the Salmon, in their passing 



